ABSTRACT Glioblastoma (GBM) continues to be an invariably fatal malignancy with limited treatment options. Our laboratory studies tumor metabolism and its potential to serve as a novel therapeutic target. Through a series of investigations, our group has identified that the diverse tumor ecology implicit in this malignancy contributes to considerable intratumoral metabolic heterogeneity and dynamic metabolic reprogramming, allowing GBM cells to adapt and proliferate under diverse, microenvironmental stresses. Specifically, through integrative cross-platform analyses coupling metabolomics with genomics in patient-derived tumors, we identified enhanced fatty acid oxidization (FAO) as a metabolic node in GBM driven by a transcriptional program designed to import and utilize fatty acids from the tumor microenvironment. This metabolic phenotype was specific to the mesenchymal subtype in GBM and recapitulated in preclinical models. Functional analyses uncovered specific roles these fatty acids play in gliomagenesis, which are dependent upon nutrient availability. In a state of glucose deprivation, mesenchymal GBM cells utilize these exogenous fatty acids to serve as a vital, alternate source of ATP, whereas in nutrient favorable conditions, the intermediary metabolism of FAO acts as a metabolic cue to drive a transcriptional program supporting cellular proliferation and mesenchymal differentiation. Accordingly, inhibiting FAO in standard, nutrient rich conditions led to decreased proliferation, however, robust energetic stress and non-apoptotic cell death was observed in mesenchymal GBM cells in the context of glucose deprivation. In this application, we propose to extend these promising findings by defining molecular mechanisms governing enhanced FAO in GBM (Aim 1), delineating the multiple roles FAO may play in gliomagenesis in the context of this tumor?s diverse tumor ecology (Aim 2), and evaluate the translational potential for eliciting metabolic synthetic lethality in GBM through energetic stress (Aim 3).